Yarn in this invention is defined as a continuous strand of textile filament having a number of individual heterofilaments laid together without twist.
Multifilament composite yarns are disclosed in U.S. Pat. No. 3,645,819. Such yarns are characterized as a unit composite having a core component and matrix or sheath component whose melting point is different from that of the core component, and assembling a plurality of the unit composites into a bundle and melting the sheath component forming a composite yarn. Polymeric material used include polyamide, polycaprolactum, polyhexamethylene-adipoamide, polyethylene terephthalate, polypropylene, polyethylene, polyacetal, polyvinyl chloride, polystyrene and copolymers of these polymers. The sheath component is a polyamide polymer. Also, the yarns are characterized as having a rough surface for the prevention of yarn slippage and has voids in the yarn. Such yarns are disclosed for use in tires, in particular, the chafer fabric of tires.
U.S. Pat. No. 5,162,153 discloses a sheath/core bicomponent fiber having a specific poly(butylene terephthalate) copolymer made from dimethyl terephthalate and a blended product of dimethyl adipate, dimethyl glutarate and dimethyl succinate, with butanediol and hexanediol.
The yarns of the present invention are generally used either as monofilament replacements or for use as reinforcement in industrial materials, or in various components of tires. Such uses are predicated on properties of the yarn, in particular for heterofilaments, properties of the core component. Accordingly, there is a need to find a suitable heterofilament composite yarn having a wide variety of properties that may be used in monofilament applications as well as industrial uses and as components in tires.